Communication systems have widely used surface acoustic wave (SAW) resonators due to their higher quality (Q) factors which typically are difficult to achieve with active filters. Recent developments in micro-mechanical resonators have allowed micro-mechanical resonators to replace SAW resonators since such micro-mechanical resonators tend to be less bulky than SAW resonators. However, micro-mechanical resonators often have limited resonant frequencies, typically on the order of hundreds of megahertz (MHz). Advances in bulk acoustic wave (BAW) resonator technology have allowed such BAW resonators to be utilized with conventional CMOS technology, and furthermore such BAW resonators have higher resonant frequencies typically in the gigahertz (GHz) range, allowing BAW resonators to be utilized in cellular and wireless local area network (WLAN) applications. Such resonators may exhibit both resonance characteristics and anti-resonance characteristics, where the resonance characteristic may provide a bandpass filter type function, and where the anti-resonance characteristic may provide a notch filter type function.
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